Hammerstein model-based robust control of DC/DC converters

Abstract

This paper deals with model-based robust control of DC/DC power electronic converters. The converter is modelled by means of its static characteristic and a few continuous-time linear and time-invariant (LTI) models corresponding to contiguous ranges of duty-cycle. The model appears as a Hammerstein model in which the values of the parameters of the LTI part depend on the actual duty-cycle operating range. This suggests to describe the converter as an uncertain system to be controlled using robust control techniques. Frequency domain approach is used for describing the nominal model and the uncertainty. In view of applying robust control, identification of the LTI models is performed by means of simulation experiments carried out on a converter switched model implemented on MATLAB-SIMULINK environment. Internal Model Control (IMC) structure is employed for the controller design, but its implementation is performed using the equivalent classical feedback control structure. Comparison with a PI controller, designed by means of phase margin assignment, shows the peculiarities of the proposed approach.